some test cases

pom.xml

@@ -13,6 +13,7 @@
 	</licenses>
 	<properties>
 		<spring-boot.version>1.1.4.RELEASE</spring-boot.version>
+		<spring.version>4.0.6.RELEASE</spring.version>
 		<bootstrap.version>2.3.2</bootstrap.version>
 		<jquery.version>1.11.0</jquery.version>
 		<angularjs.version>1.2.12</angularjs.version>
@@ -67,6 +68,12 @@
 			<version>4.10</version>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework</groupId>
+			<artifactId>spring-test</artifactId>
+			<version>${spring.version}</version>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 	<repositories>
 		<repository>

src/main/java/de/codecentric/boot/admin/service/ApplicationRegistry.java

@@ -15,12 +15,14 @@
  */
 package de.codecentric.boot.admin.service;
 
+import java.net.MalformedURLException;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
 import org.apache.commons.lang3.Validate;
+import org.apache.tomcat.util.net.URL;
 import org.springframework.stereotype.Service;
 
 import de.codecentric.boot.admin.model.Application;
@@ -42,12 +44,29 @@ public class ApplicationRegistry {
 	 */
 	public Application register(Application app) {
 		Validate.notNull(app, "Application must not be null");
-		Validate.notNull(app.getId(), "Application ID must not be null");
-		Validate.notNull(app.getUrl(), "Application URL must not be null");
+		Validate.notNull(app.getId(), "ID must not be null");
+		Validate.notNull(app.getUrl(), "URL must not be null");
+		Validate.isTrue(checkUrl(app.getUrl()), "URL is not valid");
 		return registry.put(app.getId(), app);
 	}
 
 	/**
+	 * Checks the syntax of the given URL.
+	 * 
+	 * @param url
+	 *            The URL.
+	 * @return true, if valid.
+	 */
+	private boolean checkUrl(String url) {
+		try {
+			new URL(url);
+		} catch (MalformedURLException e) {
+			return false;
+		}
+		return true;
+	}
+
+	/**
 	 * Checks, if an application is already registerd.
 	 * 
 	 * @param id

src/test/java/de/codecentric/boot/admin/service/ApplicationRegistryTest.java

+package de.codecentric.boot.admin.service;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import de.codecentric.boot.admin.config.WebappConfig;
+import de.codecentric.boot.admin.model.Application;
+
+@ContextConfiguration(classes = { WebappConfig.class })
+@RunWith(SpringJUnit4ClassRunner.class)
+public class ApplicationRegistryTest {
+
+	@Autowired
+	private ApplicationRegistry registry;
+
+	@Test(expected = NullPointerException.class)
+	public void registerFailed1() throws Exception {
+		registry.register(new Application());
+	}
+
+	@Test(expected = NullPointerException.class)
+	public void registerFailed2() throws Exception {
+		Application app = new Application();
+		app.setId("abc");
+		registry.register(app);
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void registerFailed3() throws Exception {
+		Application app = new Application();
+		app.setId("abc");
+		app.setUrl("not-an-url");
+		registry.register(app);
+	}
+
+	@Test
+	public void register() throws Exception {
+		Application app = new Application();
+		app.setId("abc");
+		app.setUrl("http://localhost:8080");
+		registry.register(app);
+	}
+
+	@Test
+	public void isRegistered() throws Exception {
+		Application app = new Application();
+		app.setId("abc");
+		app.setUrl("http://localhost:8080");
+		registry.register(app);
+
+		assertFalse(registry.isRegistered("xyz"));
+		assertTrue(registry.isRegistered("abc"));
+	}
+
+	@Test
+	public void getApplication() throws Exception {
+		Application app = new Application();
+		app.setId("abc");
+		app.setUrl("http://localhost:8080");
+		registry.register(app);
+
+		assertEquals(app, registry.getApplication("abc"));
+	}
+
+	@Test
+	public void getApplications() throws Exception {
+		Application app = new Application();
+		app.setId("abc");
+		app.setUrl("http://localhost:8080");
+		registry.register(app);
+
+		assertEquals(1, registry.getApplications().size());
+		assertEquals(app, registry.getApplications().get(0));
+	}
+
+}